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Tuesday, December 6, 2016

The lowdown on lithium batteries..... the coolest, & hottest battery for tech

L-ion Batterys, (Lithium Ion Batterys), are a pretty amazing piece of technology and very popular. You can find them in cell phones, pdas, laptops, gps devices...etc.

They hold a "higher energy density" per pound. They pack more punch per pound more than any other battery type. Including Nickle Metal Hydide (NiMH) which can be found in hybrid cars like the Toyota Prius and the Honda Insight.
Because of that, the automotive industry is seeing l-ion batterys as a replacement for the NiMH batteries. Currently the Chevy Volt & the Nissan Leaf use the L-ion batteries. Other companies are soon to follow. One big issue they have to tackle is that lion batteries don't do well with extreme temperatures.

So how do they work and what is with them exploding in cell phones?

Background

Lithium by nature is an unstable metal however lithium ions are much safer.

In 1979, solid state physicist John B Goodenough

discovered that by using lithium cobalt oxide as a cathode of a lithium-ion rechargeable battery, it was possible to achieve a high density of stored energy with an anode other than metal. His last name is certainly ironic! (are they "good enough"?)

In 1991 the Sony Corporation started commercializing lithium iion batterys and L-ion batterys started replacing nickle cadmium batterys (Nicad) in the late 1990s.

How they work

L-ion batterys work by the same principle as any other battery does. The transfer of electrons between a cathode (positive) and an anode (negitive). The only difference is the chemical composition within the cells. And the fact that with rechargeable batteries the charge is reversed as well.

They're also low maintenance which is a big advantage over other battery types. They require no memory so no cycling is required like the old Nicad batteries.

But they do have drawbacks. L-ion batteries have voltage protection circuits to prevent overcharging and prevent cell voltage from dropping to low during discharge. They contain temperature sensors for monitoring battery temp. If a battery gets to hot, the protection circuit sends a signal to the device to shut down to prevent damage.L-ion batteries prefer a partial discharge rather than a deep discharge.
If the voltage drops down to a certain voltage, the cells are ruined.

What's with exploding batteries?

L-ion batteries hold together positive and negative terminals (cathodes and anodes) along with a polymer that separates the two sides. This is all sandwiched together a tightly wrapped container, but instead of a paste which is found in normal batteries, it's a lithium ionized liquid which is extremely flammable. The manufacturing process creates small minute pieces of metal that float in the liquid. These pieces are removed but the manufacture can't completely remove 100% of these metal flakes.

As you may have seen on the news, Samsung recently recalled the ENTIRE production line of their Galaxy Note 7s due to exploding batteries costing the company over 5.3 billion.

There are two scenarios which can cause a L-ion battery to explode

Heat: The issue lies when the battery starts to get hot, possibly from being on the charger....in someones pockets,,,or left on the dash of a car on a summer day.
When that happens the fluid inside the battery becomes thinner allowing the small pieces of metal to move more freely. If a piece of metal comes in contact with the separator, a short circuit will occur. When a short circuit occurs in a flammable liquid it's not a pretty sight.

Aggressive technology design flaw: Or what you could call "pushing the safety boundary" - Cell phone manufactures are always seeking to push more power into smaller batteries and wanting a flatter battery in the design phase. The flatter the battery the thinner the components must be inside the battery.....to a point where the polymer separators may not be effective in separating the negative and positive sides.

This manufacturing error allowed the plates to make contact and a short circuit followed creating an enormous amount of heat to the point where the battery exploded.

If you have a Samsung Note 7,please contact your carrier directly or call Samsung Customer service at 1-844-365-6197 for assistance. Visit Samsung Note 7 recall for further information.

The hazards and issues with lithium batteries are rare. But for their small compact size, they pack a good punch and the tech industry sees anything smaller with more power a big advantage.